1. Field of the Invention
The present invention broadly relates to high temperature fabrication of parts, such as by brazing or the like, and, more particularly, is concerned with a corrutherm expansion fixture for supporting a past during brazing thereof.
2. Description of the Prior Art
Generally, the term "brazing" is applied to that group of welding processes in which metal components are joined together by means of a nonferrous filler metal or alloy medium having a melting point above 800.degree. F. but below that of the base metals or alloys of the components. In the brazing operation, the components are heated but not melted while the brazing medium is melted. The melted medium wets the surfaces of the components to be joined, creeps into and through each joint by capillary action, and adheres to the surfaces by alloying and diffusion bonding therewith.
Brazing processes are widely used in industry for the fabrication of parts from a variety of metals and alloys. Furnace brazing is particularly suited for fabrication of an assembly en masse wherein the joining of a multitude of parts is required. As the assembly is heated in the furnace, all joints in the assembly are completed at the same time regardless of their inaccessibility, shape, depth or number.
In furnace brazing of various assemblies, particularly those which are tubular or cylindrical shaped, it is conventional practice to use ring-shaped support fixtures and rely on the thermal expansion of the ring material for supporting the assembly during the brazing operation. However, in thermal expansion of the full ring, control of the expansion force required to support the assembly is regulated by changing the temperature of brazing operation or by selecting a ring material having a coefficient of thermal expansion properly matched to the materials which form the components of the assembly. The expansion force requirement will vary, depending upon the construction, configuration, and metal composition of the assembly or part to be brazed.
The present techniques of changing the brazing temperature or selecting a material of a particular coefficient of thermal expansion require that a complex analysis be performed for each individual assembly since the expansion force requirement for each assembly differs. It would be desirable to find a way to regulate the expansion force level in a manner simpler than that presently practiced. For instance, it would be advantageous to be able to evolve an expansion fixture design which has a more general purpose application than has been the case heretofore.